The dam, which controls the water and power supplies to large areas of Iraq, has become a key battleground.

The US said Iraqi troops and Kurdish peshmerga fighters recaptured the dam with American assistance on Monday.

IS fighters have waged a violent campaign in Iraq and Syria, seizing large swathes of both countries.

The violence has displaced an estimated 1.2 million people in Iraq alone.

Image copyrightReutersImage caption
US aircraft have targeted the area around the strategically important Mosul Dam

How many foreign fighters are in IS?

There are estimated to be about 3,000 citizens from Western countries currently fighting for IS in Iraq and Syria, the London-based Royal United Service Institute (Rusi) says.

According to Rusi, the majority are believed to be from the UK, Belgium, the Netherlands, Germany, France and the Nordic nations.

The UK government says up to 400 British nationals are fighting alongside militant groups.

But these jihadists are said to be far outnumbered by volunteers from Arab nations such as Tunisia, Morocco and Saudi Arabia.

A June 2014 report from the New York-based consultancy the Soufan Group suggested people from at least 81 different countries had become involved, including citizens from Australia, the US, Canada, Ireland, and Spain.